1. Field of the Invention
This invention relates to an age-hardened copper titanium alloy having improved properties.
2. Description of the Prior Art
A lot of electrically conductive springs of thin plate type are made of an age-hardened copper titanium alloy because of its excellent mechanical strength and electrical conductivity. Such spring sheets are usually produced by a process which includes preparing a copper titanium melt, casting it, hot working the cast copper titanium, subjecting the hot-worked copper titanium to alternate annealing and cold working to final shape, subjecting the copper titanium to solution heat treatment, and age-hardening it after cold working, if required. Its solution heat-treated structure has, however, an average crystal grain size of at least 40 microns and even up to 100 microns.
The age-hardened copper titanium alloy has been developed as an inexpensive substitute for a well-known age-hardened copper beryllium alloy which is disclosed in, for example, U.S. Pat. No. 4,425,168 issued to Goldstein et al. on Jan. 10, 1984. The conventional age-hardened copper titanium alloy is, however, not satisfactory, and required to be improved, in view of mechanical properties such as formability, fatigue strength, elongation and yield strength. Moreover, it has the drawback of having different properties in the rolling direction and in a direction perpendicular thereto.